BRYOZOA, WITH DESCRIPTIONS OF NEW SPECIES. 371 
them, and, consequently, it bags out, giving to the upper portion 
a flounced appearance, particularly in the latter, Pl. III. fig. 1 ¢. 
The tentacles themselves, in all these genera, are rather stout 
and linear with the end obtuse; they have the appearance of 
being tubular, as have likewise the oral arms of Plumatella : the 
tentacles are clothed with long cilia, which vibrate upwards on 
one side, and downwards on the other, in the same manner as de- 
scribed in the marine species ; and as in them, when the polype 
is retracted, the tentacles are drawn down in an erect position, 
having first been brought together into a compact linear bundle, 
Pl. III. fig. 2 a, and Pl. V. fig. 2d. They do not appear to be at all 
contractile, and in all the species are transparent and almost homo- 
geneous in their structure. There can be little doubt that they 
are not merely tentacles, but that they are likewise respiratory 
organs: food is brought to the mouth by their ciliary currents, 
‘and also by the action of the tentacles themselves, one or more 
of which may frequently be seen bending suddenly inwards, and 
securing such particles as come within their reach. They occa- 
sionally act in concert in the capture of animalcules, by bringing 
their tips together, thus forming, in those with a circular disc, a 
very elegant oval cage, within which the imprisoned prey may 
be seen for an instant or two dashing about, previously to passing 
into the cesophagus or to liberation, which not unfrequently hap- 
pens, the captive proving distasteful to the polype. The tentacles 
then may be considered prehensile, labial, or oral appendages, not- 
withstanding their respiratory function, and as such they area 
portion of the alimentary system. 
The oral orifice of Plumatella is semicircular, Pl. LV. fig. 3 a, 
and protected by a strong, rounded, fleshy valve, 6, which, arising 
from the side of the mouth at the point on the inner margin of 
the cresent, where the two arms unite, projects upwards and 
slightly overhangs the opening. This valve is completely under 
the control of the animal, and can be made to act as a sort of 
operculum, closing the orifice to prevent the admittance of food ; 
or it can be used to force food into the pharynx. The mouth, 
Pl. IIT. fig. 1 d, of Predericella is likewise semicircular, and is 
also provided with a similar valve, e. It is immediately behind 
